generate-git-snapshot: prepend "origin" when checking out a $branch

otherwise we might be checking out a branch which doesn't exist locally yet,
failing with:

| fatal: git checkout: updating paths is incompatible with switching branches.
| Did you intend to checkout '$BRANCH' which can not be resolved as commit?

Thanks: Stefan Schlesinger <sts@ono.at> for the bug report and testing
Adding freight support to build-and-provide-package
Add UDebComponents. Needed by some packages.
Merge branch 'sts/freight_support' of https://github.com/sts/jenkins-debian-glue
Support configuration of release repository via $RELEASE_REPOSITORY

Thanks: Marcel Beck <nexeck@outlook.com> for the initial patch in
pull-request 34 which triggered development of this feature
Provide configuration example for REPOSITORY in default config
Bump Standards-Version to 3.9.4
Release new version 0.5.0
invoke 'reprepro include' cmdline with --ignore=uploaders

Quoting https://github.com/mika/jenkins-debian-glue/issues/36 ->

| If Jenkins tries to upload in an existing repository that have an
| Uploaders: configuration, it will fail because the keys are not
| signed. The simple fix is to pass --ignore=uploaders to reprepro
| include or to sign packages when building them.

As documented in the reprepro manpage:

| Uploaders
|    Specifies a file (relative to confdir if not starting with a
|    slash)  to  specify  who  is  allowed  to upload  packages.
|    Without this there are no limits, and this file can be ignored
|    via --ignore=upload‐ ers.  See the section UPLOADERS FILES below.

Closes: #36
Thanks: anarcat for the bug report and suggestion
generate-reprepro-codename: drop default DebIndices/DscIndices settings

Closes #35
Thanks: anarcat for the bug report and suggestion
generate-reprepro-codename: drop AlsoAcceptFor default setting

This should also be redundant, as noted in github issue #35

Thanks: anarcat
puppet/apply.sh: provide fallback for EC2 IP retrieval

Debian's AMI[1] doesn't provide anything
inside 'facter ec2_public_ipv4', so let's try
the manual approach then before really falling
back to 'ip addr ...' hackery to avoid retrieval
of internal IP on Debian's AMI/EC2 system.

[1] http://wiki.debian.org/Cloud/AmazonEC2Image